Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C271/00—Derivatives of carbamic acids, i.e. compounds containing any of the groups, the nitrogen atom not being part of nitro or nitroso groups
  • C07C271/06—Esters of carbamic acids

Definitions

• This invention relates to a process for the preparation of N,N-disubstituted mono and oligourethanes.
• N-aryl substituted monourethanes may be N-alkylated under the conditions of phase transfer catalysis.
• secondary alkylating agents may be used in this process, the method completely fails with N-aliphatically substituted urethanes (See S. Julia, A. Ginebreda, Anales de Quimica (Madrid), Volume 75, page 348, lines 7 to 13).
• the solvent used is either methylene chloride or dimethyl sulphoxide or methyl ethyl ketone.
• Triethyl benzyl ammonium chloride is used in all cases as a phase transfer catalyst. These solvents have disadvantages which in some cases considerably reduce the reaction yields.
• methylene chloride itself acts as an alkylating agent under these reaction conditions while methyl ethyl ketone forms aldol type by-products by auto condensation.
• Dimethyl sulphoxide forms toxic, malodourous by-products and is difficult to remove from the reaction products.
• phase transfer catalysts required for the reactions make it difficult to work up the reaction mixtures due to the formation of emulsions. A great effort is required to remove them completely from the reaction products.
• N-aliphatically, N-cycloaliphatically or N-araliphatically substituted mono and oligourethanes are reacted with alkylating agents in the presence of an at least equivalent quantity of a solid metal hydroxide, either without solvents or in an aprotic organic solvent.
• a phase transfer catalyst may optionally be present.
• the present invention relates to a process for alkylating N-aliphatically monosubstituted urethanes.
• N,N-disubstituted mono- and oligourethanes corresponding to the general formula(e) ##STR1## in which n is an integer from 1 to 6, preferably from 1 to 4,
• n 1 is an integer from 1 to 6, preferably from 1 to 3,
• R 1 represents an aromatic hydrocarbon group having 6 to 18 (preferably 6 to 13) carbon atoms, an aliphatic hydrocarbon group having 1 to 18 (preferably 1 to 6) carbon atoms, a cycloaliphatic hydrocarbon group having 4 to 30 (preferably 6 to 15) carbon atoms or an araliphatic hydrocarbon group having 7 to 30 (preferably 7 to 15) carbon atoms,
• R 2 represents an aliphatic hydrocarbon group having 1-18 (preferably 2-8) carbon atoms, a cycloaliphatic hydrocarbon group having 4-30 (preferably 6-15) carbon atoms or an araliphatic hydrocarbon group having 7-20 (preferably 7-13) carbon atoms,
• R 3 represents an aromatic hydrocarbon group having 6-18 (preferably 6-13) carbon atoms, an aliphatic hydrocarbon group having 1-18 (preferably 1-12) carbon atoms, a cycloaliphatic hydrocarbon group having 7-30 (preferably 7-15) carbon atoms or an araliphatic hydrocarbon group having 7-30 (preferably 7-15) carbon atoms,
• urethanes corresponding to the formula(e) ##STR2## in which n, n 1 R 1 and R 2 have the meanings indicated above with alkylating agents in the presence of at least equivalent quantities of a solid metal hydroxide, either solvent free or in an aprotic organic solvent and optionally in the presence of a phase transfer catalyst.
• aprotic organic solvent preferably chlorobenzene, dimethylformamide or N-methyl pyrrolidone
• metal hydroxide preferably sodium or potassium hydroxide
• phase transfer catalyst may be omitted without incurring any disadvantages and working up of the reaction mixture is thereby considerably simplified.
• the process of the present invention surprisingly provides N,N-di-substituted urethanes by a simpler and more economical procedure and with higher yields, higher volume/time yields and greater purity, especially on a technical scale.
• the metal hydroxides used in the present process are less expensive, quite safe and easier to handle.
• N-aliphatically substituted urethanes can also be alkylated by the process of the present invention.
• the urethane used as starting material for the process of the present invention may be prepared, for example, by the reaction of aliphatic mono- or oligoisocyanates with mono- or di- to hexahydric alcohols by known methods, either solvent free or in solution, optionally in the presence of a catalyst.
• urethanes may also be prepared, for example, by the condensation of primary mono- or oligo-amines with chloroformic acid esters of mono- or di- to hexahydric alcohols. They may, of course, also be prepared by the reaction of carbamic acid chlorides with alcohols.
• Alcohols which may be used for the preparation of the urethanes used as starting materials in the process of the present invention include alcohols of the formula
• n an integer from 1 to 6 (preferably 1 to 4), and
• R 1 represents an aromatic hydrocarbon group having 6 to 18 (preferably 6 to 13) carbon atoms, an aliphatic hydrocarbon group having 1 to 18 (preferably 1 to 6) carbon atoms, a cycloaliphatic hydrocarbon group having 4 to 30 (preferably 6 to 15) carbon atoms or an araliphatic hydrocarbon group having 7 to 30 (preferably 7 to 15) carbon atoms.
• Such alcohols include monohydric alcohols of the kind described in Ullmanns Enzyklopadie der Technischen Chemie, Volume 7, pages 205-206, 4th Edition, 1974, as well as phenols and substituted phenols.
• polyhydric alcohols examples include: ethylene glycol, (1,2)- and (1,3)-propylene glycol, (1,4)- and (2,3)-butylene glycol, (1,6)-hexane diol, (1,8)-octanediol, neopentyl glycol, 1,4-bis-hydroxy methyl cyclohexane, 2-methyl-1,3-propanediol, glycerol, trimethylol propane, (1,2,6)-hexanetriol, (1,2,4)-butanetriol, trimethylol ethane, pentaerythritol, quinitol, mannitol, sorbitol, formitol, methylglycoside and/or 1,4-, 3,6-dianhydrohexitols as well as polyvalent phenols such as pyrocatechol, resorcinol, hydroquinone and polynuclear phenols, such as bisphenol A. Mix
• Isocyanates which may be used for the preparation of the urethanes used as starting materials correspond to the general formula
• n 1 represents an integer from 1-6 (preferably 1-3), and
• R 2 represents an aliphatic hydrocarbon group having 1-18 (preferably 2-8) carbon atoms, a cycloaliphatic hydrocarbon group having 4-30 (preferably 6-15) carbon atoms or an araliphatic hydrocarbon group having 7-20 (preferably 7-13) carbon atoms.
• isocyanates include: isocyanato-methane, -ethane, -propane, -butane, -pentane, and -hexane; 6-chlorohexyl isocyanate; isocyanatocyclohexane; benzyl isocyanate; tetramethylene diisocyanate; hexamethylene diisocyanate; decamethylene diisocyanate; 1,3-di-(3-isocyanatopropoxy)-2,2-dimethyl propane; (1,4)-cyclohexane diisocyanate, (2,4)-methyl cyclohexane diisocyanate, methyl cyclohexane (2,6)-diisocyanate; 1,3-diisocyanatocyclohexane; mixtures of (2,4)-methyl cyclohexane diisocyanate and (2,6)-methyl cyclohexane diisocyanate; di
• alkylating agents used in the process of the present invention include those corresponding to the formula
• R 3 represents an aromatic hydrocarbon group having 6-18 (preferably 6-13) carbon atoms, an aliphatic hydrocarbon group having 1-18 (preferably 1-12) carbon atoms, a cycloaliphatic hydrocarbon group having 7-30 (preferably 7-15) carbon atoms or an araliphatic hydrocarbon group having 7-30 (preferably 7-15) carbon atoms, and
• X represents a suitable removable substituent such as halogen atom or a sulfate, sulfonate, phosphate or phosphonate group.
• the hydrocarbon R 3 may, of course, carry other functional groups in addition to the group X, provided they are inert under the reaction conditions or react in a well defined manner with the reactants according to the invention.
• functional groups include: nitro groups, certain ester, urethane, amide and sulfonyl groups, unactivated, aromatically bound halogen, epoxide groups, aziridine groups, ether groups and thioether groups.
• alkylating agents include: methylchloride and bromide, ethylchloride and bromide, propylchloride and bromide, i-propylchloride and bromide, n-butylchloride and bromide, isobutylchloride and bromide, cyclohexylchloride and bromide, octyl, nonyl, decyl, undecyl and dodecyl chloride and bromide, benzyl chloride and bromide, allylchloride and bromide, p-nitro benzylchloride and bromide, 2,4-dinitrochlorobenzene, 2,4-dinitrofluorobenzene, 2,4,6-dinitrochlorobenzene, 2,4,6-dinitrofluorobenzene, dimethylsulfate, diethyl sulfate, the methyl ester and ethyl ester of
• alkylating agents methyl chloride and bromide, ethyl chloride and bromide, dodecyl chloride and bromide, allylchloride and bromide, benzyl chloride and p-tosyl ester.
• reaction is preferably carried out in an autoclave under pressure.
• reaction of urethane with alkylating agent may be carried out either in an aprotic organic solvent or in excess, liquified alkylating agent, optionally in the presence of a phase transfer catalyst.
• the bases used in the process of the present invention are solid, preferably finely powdered metal hydroxides such as alkali metal hydroxides (e.g., potassium or sodium hydroxide). Sodium hydroxide is preferred on economic grounds.
• alkali metal hydroxides e.g., potassium or sodium hydroxide
• Sodium hydroxide is preferred on economic grounds.
• the hydroxide of lithium, rubidium or barium, for example, or moist silver oxide may, of course, also be used. It may in some cases be advantageous to use mixtures of these metal hydroxides.
• the metal hydroxides are used in equivalent quantities based on the amount of urethane groups.
• the above described urethanes used as starting materials may be reacted with the alkylating agent in stoichiometric quantities, less than stoichiometric quantities or in excess (based on the number of urethane groups present in the molecule). It is preferred to use 0.3-5 mol, particularly 1-2 mol of alkylating agent for each mol of urethane groups. Only partial alkylation is, of course, obtained when a subequivalent quantity of alkylating agent is used but the use of a substantial excess of alkylating agent is uneconomical.
• the process of the present invention is generally carried out at a temperature of 0°-180° C., preferably 10°-80° C. and most preferably at room temperature, under excess pressure or reduced pressure or, preferably without application of pressure, and either continuously or batch-wise.
• the dwell time may be, for example, 0.5 to 24 hours and is preferably in the region of 0.5 to 10 hours.
• the reaction may be carried out in excess alkylating agent, or preferably, in an aprotic organic solvent.
• Aprotic organic solvents which are inert under the reaction conditions according to the invention may be used.
• suitable solvents include: benzene, toluene, xylene, ethylbenzyl, cumene, methylene chloride, chloroform, dichlorobenzene, trichlorobenzene, nitrobenzene, acetone, methylethyl ketone, diethyl ketone, cyclohexanone, diethyl ether, diisopropyl ether, tetrahydrofuran, dioxane, dimethylformamide, dimethyl acetamide, dimethyl sulfoxide, tetramethylene sulfone, furfurol.
• nitromethane, nitroethane, nitropropane, N-methyl pyrrolidone and hexamethylene phosphonic acid triamide Chlorobenzene, dimethylformamide, N-methyl pyrrolidone and tetramethylene sulfone are preferred.
• phase transfer catalyst It may in some cases be advantageous to carry out the reaction in the presence of a phase transfer catalyst.
• Catalysts of this kind are described, for example, by E. V. and S. S. Dehmlow in Phase Transfer Catalysis, 2nd Edition, Verlag Chemie 1983. Quaternary ammonium and phosphonium salts corresponding to the formula: ##STR3## are suitable catalysts.
• Z represents nitrogen or phosphorus and R', R",R"' and R"", which may be identical or different, each represents an alkyl group with 1-18 carbon atoms although one of the groups may be an araliphatic group containing 7-15 carbon atoms, and the sum of carbon atoms of the four groups is preferably 12 to 29 and A.sup.(-) represents an halogenide or phosphonate.
• catalysts N-benzyl-N,N,N-triethyl-ammonium chloride or bromide, N-benzyl-N-dodecyl-N,N-dimethyl-ammonium chloride or bromide, N,N,N,N-tetra-n-hexyl-ammonium chloride or bromide, N-benzyl-N,N,N-tri-n-octyl-ammonium chloride or bromide and phosphonium salts corresponding to these ammonium salts.
• the quaternary ammonium and phosphonium salts mentioned as examples are preferably put into the process of the present invention in a solvent free form or as aqueous solutions (for example, with a solids content of 30 to 60 wt. %) and preferably in a quantity of 1-10 mol %, based on the molar number of urethane groups present.
• Phase transfer catalysts may be omitted without any deleterious effect if polar aprotic solvents such as dimethylformamide, N-methyl-pyrrolidone, dimethyl sulfoxide or sulfolan are used.
• polar aprotic solvents such as dimethylformamide, N-methyl-pyrrolidone, dimethyl sulfoxide or sulfolan are used.
• the process according to the invention may be carried out, for example, by introducing the urethane, alkylating agent and optional catalyst into the selected solvent and the solid, finely ground metal hydroxide may then be added either portion-wise or continuously with stirring and optionally cooling.
• the reaction mixture may then be stirred at room temperature or optionally at elevated temperature until thin layer chromotographic or gas chromatographic analysis shows complete conversion.
• the product may be worked up by known methods. When water-miscible solvents are used and the reaction products are solid and insoluble in water, the reaction mixture may be stirred into water and the precipitated reaction product may then be isolated by suction filtration in the usual manner. If the reaction products are oily, they are suitably worked up by one of the usual methods of extraction. The crude products may, if necessary, be purified by conventional methods such as recrystallization or distillation.
• the N,N-disubstituted urethanes which may be prepared by the process of the present invention are active ingredients and valuable starting materials for the preparation of dyes, pharmaceutical products and thermostable synthetic materials.
• the N,N-disubstituted urethanes produced in accordance with the present invention in particular show greater thermal, thermooxidative and photooxidative stability (see R. Vieweg, A. Hochtlen, Kunststoff Handbuch Volume VII, Polyurethane, Hanser Verlag, Kunststoff 1966, pages 11 and 21) and better fire characteristics than the corresponding N-monosubstituted urethanes.
• the corresponding substituted secondary amines may be prepared by hydrolysis of the N,N-disubstituted urethanes. These amines are also important starting materials for the synthesis of active ingredients and the preparation of formulations for synthetic materials.
• IR spectroscopy in particular provides a convenient method of checking the rate of conversion since the characteristic bands for N-monosubstituted urethanes at 3200-3500 cm -1 (N--H) and 1530-1560 cm -1 (N--H) disappear in the course of the reaction.
• NMP N-methyl-pyrrolidone

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• 1986
  • 1986-03-22 DE DE19863609813 patent/DE3609813A1/de not_active Withdrawn
• 1987
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  • 1987-03-09 AT AT87103345T patent/ATE50563T1/de not_active IP Right Cessation
  • 1987-03-09 EP EP87103345A patent/EP0238925B1/de not_active Expired - Lifetime
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  • 1987-03-16 US US07/025,910 patent/US5130457A/en not_active Expired - Fee Related
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